Coupling arrangement for vessels

ABSTRACT

A tugboat engages the stern of a barge using a linkage which permits freedom of movement between the two vessels for pitching, rolling, and/or heaving motions, but yet permits the tug to push and steer the barge. A large pin protruding from the bow of the tug extends into a vertical slot in the stern of the barge, the pin and slot being along or parallel to the centerlines of the vessels. Rigid struts connect the tug to the barge, these being positioned at angles with respect to the vessels. Swivel or hinge joints are used for connecting the struts to the vessels to permit relative movement of the struts and vessels. The pin may be cylindrical, or curved at its sides, to permit rolling motion. The length of the pin and the depth of the slot may be such that slight fore-and-aft movement is permitted as would occur in pitch or roll. A wide recess in the stern of the barge may be provided to accommodate the bow of the tug.

0 United States Patent l 13,568,62l

[72] Inventor Masasuke Kawasaki 3,035,536 5/ 1962 Archer 114/77 21 1 ppNo gigg f shdeu 70458 Primary Examiner-Trygve M. Blix v Filed g, 6 1970Attorneys-Arnold, White & Durkee and John 6. Graham [45] Patented Mar.9,1971

Continuation-impart of application Ser. No. 784,511, Nov. 19, 1968,abandoned, which is a confinuafiomimpm of .aBSTkACfl: A tugboat engagesthe stern of a barge using a amnion sen 714,558, Man 20 linkage whichpermits freedom of movement between the two 1968" gg haaia vessels forpitching, rolling, and/or heaving motions, but yet permits the tug topush and steer the barge. A large pin protruding from the bow of the tugextends into a vertical slot l 54] COUPLING ARRANGEMENT FOR ss s in thestern of the barge, the pin and slot being along or para]- 36 claims, 17Drawing 8* lel to the centerlines of the vessels. Rigid struts connectthe tug to the barge, these being positioned at angles with respect [52]11.8. CI. 114/235 to the vessels Swivel or hinge joints are used fconnecting 1 21/00 the struts to the vessels to permit relative movementof the [50] Field of Search 1 14/235, 77 struts and vessels The pin maybe cylindrical or curved at its sides, to permit rolling motion. Thelength of the pin and the [56] References cited depth of the slot may besuch that slight fore-and-aft move- UNITED STATES PATENTS ment ispermitted as ,would occur in pitch or roll. A wide 1,038,676 9/1912Stevens 114/235 recess in the stem of the barge may be provided toaccom- 2,984,202 5/1961 Lunde 1 14/235 modate the bow of the tug.

PATENTEDHAR 91ml $558, 21

I sum 10F 4 M. KAWASAK/ ATTORNEYS PATENIED mm 9 I97l 3; 568,621

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M. KAWASAKI /4 INVISN'IUR.

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- ATTORNEYS PATENTEDHAR 9:97: 3.568.621

sum 3 or a M. Kawasaki INVE N TOR A LKOed 2 7 W 3 GUAM ATTORNEYSPATENTED MAR 9197:

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M Kawasaki Amvfd WM & Uwdee ATTORNEYS FIG/2a CGUPLING ARRANGEMENT lFGRVESSELS This application is a continuation-in-part of copendingapplication Ser. No. 784,511, filed Nov. 19, 1968, now abandoned whichin turn was a continuation-in-part of thencopending application Ser. No.714,558, filed Mar. 20, 1968, now abandoned.

in the marine industry, it has been found that the use of tug and bargecombinations for transporting cargos by water in many respects iseconomically superior to the use of selfpropelled vessels. However, tugand barge combinations have certain disadvantages in comparison toself-propelled vessels, from the viewpoint of technical and operationalconsiderations. Specifically, when a tug tows a barge thesedisadvantages involve the additional resistance of the tug which is inthe order of the resistance of the barge itself above a certain speed,and the inherent resistance characteristic of the design of barge forms,including the resistance of the skegs of the barge.

Considerable effort has been made in the marine industry to overcome theaforementioned technical and operational disadvantages of the tug andbarge combination. The resistances have been eliminated successfully byplacing the tug aft of the barge so that the barge is pushed rather thantowed. Such an arrangement has proven satisfactory in relatively calmwater. It has not, however, been found reliable in rough water, due tothe unsatisfactory coupling arrangements between the tug and barge inthe prior art. It thus has been desirable to develop a couplingarrangement for a tug and barge combination which is suitable for useunder all weather conditions, and particularly suitable in permittingfreedom in trimming, rolling, pitching and heaving, while providingsufficient rigidity between the tug and barge in turning and sidedrifting, as well as propulsion thrust fore-and-aft.

It is a primary feature of the invention to provide a couplingarrangement for vessels, such as a tug and barge combination, whereinfore-and-aft propulsion thrust is transferred through the coupling, andsteering moment is permitted, but the vessels have considerable freedomof movement with respect to one another for other linear and rotationalmotions, including pitch, heave, changes in draft, etc., as well asrolling motions in some cases. Another feature is the provision of a tugand barge coupling arrangement which is able to withstand the forcesencountered in heavy seas, but yet does not require unduly heavy andbulky structures for the coupling mechanism. Also, a feature is thefacility with which the coupling mechanism may be connected to existingvessels, or built into new vessels, without excessive alteration of theremaining structures.

In accordance with a preferred embodiment of the invention, the couplingarrangement basically comprises a vertical slot at the end of onevessel, and a protruding pin at the end of the other vessel, with thepin being shaped in some cases to allow it to rotate in the slot as wellas move up and down. Also, a pair of struts connect the two vessels,those struts being preferably rigid bars coupled to both vessels byswivel or hinged joints and angularly positioned with one on each sideof the slot and pin.

Novel features believed characteristic of the invention are set forth inthe appended claims. The invention itself, however, as well as furtherfeatures and advantages thereof, may best be understood by reference tothe following detailed description of particular embodiments, when readin conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic representation in perspective of a tug and bargecombination, illustrating principles related to the invention; 1

FlG. 2 is a plan view of a tug and barge coupled according to oneembodiment of the invention;

EEG. 3 is an elevation view of the combination of FIG. 2;

PEG. d is a plan view of a tug and barge according to another embodimentof the invention;

FIGS. 5a-5c are schematic representations of a tug and barge combinationillustrative of concepts of the invention;

l lG. s is a detail view of a swivel joint used to connect the linkagebars to the tug and barge;

. FIGS. 7, 7a and 7b are detail view of the protruding member on the bowof the tug in FIGS. 2-4 according to various embodiments of theinvention;

FIG. 8 is a pictorial view of another embodiment of the inventionemploying a different connecting arrangement for the bars;

FIG. 9 is a plan view of a tug-and-barge coupling according to anotherembodiment of the invention;

FIG. ltl is an elevation view of the coupling arrangement of FIG. 9;

FIG. ill is a front elevation view in section of the couplingarrangement of FIGS. 9 and 10; and

FIGS. 12a and 1212 are plan and elevation views, respectively, of acoupling arrangement according to another embodiment.

It will be noted that like parts appearing in several views of thedrawing will bear like reference numerals. The drawings are a part ofthis specification and are incorporated herein.

Referring now to FIG. 1, there are illustrated in schematic form a pairof vessels to be coupled together; in the context of the preferredembodiment of the invention the vessels will include a tugboat 10 whichis to be coupled to a barge ll for the purpose of propelling the barge.Either of the vessels, or the two vessels coupled together, might tendto exhibit linear motion in either of the X, Y or Z axes as illustrated,or rotational motion about either of these axes. According to theinvention, certain of these linear or rotational motions are to befreely permitted, and certain are to be constrained. In commonnomenclature, rotational motion about the X axis is referred to aspitching, rotational motion about the Y axis is rolling, and of courserotation about the Z axis is either yawing or a steering movement.Similarly, linear motion along the X axis is side drift, along the Yaxis is the desired propulsion ahead or astern, and along the Z axis isbobbing or hearing, and up-anddown movement. Also, relative movementalong the Z axis represents changes in draft, as caused by changes inloading. These three linear motions and three rotational motions willcompletely define any movement of the vessel from an analyticalstandpoint.

The objective in one embodiment is to provide complete freedom to allcomponents, with the exception of linear motion along the Y axis androtational motion around the Z axis. That is, the tugboat 10 is to pushthe barge Ii ahead or astern, and is to be considered coupled tightly tothe barge for steering moment. At the same time, the tugboat is to bepermitted to pitch, roll or bob with little constraint. The pair will beconstrained for linear motion in the X direction or for drift from sideto side except for a small degree of freedom due to the inherent natureof the coupling apparatus as will be described.

Further, a certain small degree of freedom of linear movement in thedirectionof the Y axis will be permitted due to the structure used, aswill be explained.

Turning now to FIGS. 2 and 3 of the drawings, one example of a preferredembodiment of coupling apparatus according to the invention isillustrated. The tugboat it) engages the stern of a barge ll, it beingunderstood that several of the barges II may be secured together as aunit. The coupling arrangement includes a generally vertical slot ofrecess 12 formed in the stern of the barge, and to engage the slot thereis provided a cylindrical member 14 fixed to the bow of the tug. Inaddition, a pair of struts or linkage bars 15 and 16 are provided, onebeing mounted on each side of the slot 12. The struts l5 and 16 are ofsufficient strength to bear the forces as will be described below, andare rigid along their lengths but are coupled to the stern of the bargeand to the hull of the tug by universal joints 17 which may be of thetype described with reference to FIG. 6. I

The member 14 is a cylindrical pin of adequate size and strength to bearthe forces encountered, this member protruding from the bow of the tug.The length of the pin is sufficient to permit some fore-and-aft movementfor the purposes explained with reference to FIG. 5. The pin iscylindrical to permit freedom of rolling movements of the tug withrespect to the barge. Some degree of clearance is permitted between thesurface of the pin 14 and the walls of the slot .12 to allow freemovement with respect to pitching, rolling, and slight foreand-aftmovements. Thus, the diameter of the cylindrical member 14 is almostequal to the width of the slot 12, the difference being as small aspractical. Either on the member 14 or in the slot 12 at the sidewalls,it may be appropriate to provide a shock absorbing medium such as a hardrubber bumper or the like. The bumper will affect the permittedclearance.

The combination of the cylindrical member 14 in slot 12, along with thebars 15 and 16 hingedly connected to the tug and barge by universaljoints, provides the desired freedom of movement and constrains for thecoupled vessels. Within the limits imposed by the mechanical linkage,there is complete freedom of rolling, pitching, and parallel sinkage orup and down heaving or bobbing movements. At the same time there isconstraint against relative movement between the two vessels for yawingor steering, or for fore-and-aft movement, within limits. In operation,rolling of the tug will cause the cylindrical pin to rotate in the slot12, while pitching or bobbing will cause the pin to move up and downand/or cant in a vertical plane, as will changes in loading or draft.

The length of the slot 12 would be sufficient to permit continuousmovement of the pin relative thereto, over the entire range of possiblepositions taking into account loaded or unloaded conditions of the bargeas well as violent movement of the barge and tug in heavy seas. Stopsmay be provided at the upper and lower ends of the slot to prevent thepin from being completely dislodged in the unusual event of the movementbeing extensive enough to drive the pin past the end of the slot. Whilethe slot is shown recessed into the stern of the barge, clearly the slotcould be formed as a channel attached to the stern of an existingvessel.

Referring to FIG. 4, it is noted that the coupling mechanism of theinvention is particularly adapted for use with a barge constructed inthe form of my abandoned application Ser. No. 596,652. In thisembodiment the tugboat 10 is constructed as in the example of FIGS. 1and 2, while the barge 11' defines at its stern a large verticallyextending recess 18 of sufficient size to accommodate a substantiallength of the bow of the tugboat. Also, of course, a vertical slot 12 isprovided as before to be engaged by the cylindrical member 14. Againstruts l and 16 complete the linkage, these being coupled to the sternof the barge and to the tugboat by universal joints. The advantage ofthe use of the deep recess so that the bow of the tug protrudes far intothe stern of the barge is to reduce the forces bearing upon the pin 14and the walls of the slot 12, as will be explained. Just as before, thedepth of the slot and length of the pin are selected to permit someslight fore-and-aft motion.

Turning now to FIG. 5, the purpose for permitting a small degree offreedom of movement along the Y axis will be apparent. In FIG. 5a, astern-on view of the tug and barge with both at an even keel show thestruts l5 and 16 to be of a given length. When seen in the view of FIG.5b where the tug is at a rolled position with respect to the barge, thestruts 15 and 16 must either elongate or otherwise reconcile thedifference in distance from the stem to the side of the tug between thehorizontal and the tilted positions. To this end, as seen in FIG. 5c,the tug moves inwardly with respect to the barge when the tug rolls;thus the pin 14 must be permitted to move deeper into the slot 12 sothat the distance from the stem to the side of the tug along the strutsand 16 will remain constant. Similar principles would apply for pitchingor bobbing movements. At some limit of travel, either the front end ofthe pin 14 will engage the forward wall of the slot, or else the bow ofthe tug will engage the flat portion of the stern of the barge, butwithin a wide range of relative movements this will not occur.

In the embodiment thus far described, the thrust of the tug against thestern of the barge to propel the barge or barges is transmitted throughthe linkage bars or struts 15 and 16 rather than at the bow of the tugas is the usual case. It will be seen, however, that this thrust forpropulsion is about an order of magnitude smaller than the forces whichthe linkages must be designed to withstand due to other factors. In atypical example, this thrust for propulsion may be perhaps 150,000pounds, compared to other factors of over 1 million pounds. The order ofthe forces involved may be readily approximated, using the assumptionthat the tug and barge combination is rigid. Empirical measurements haveshown that forces in any direction will be about three-fourths of theweight of the tug as a maximum under these circumstances. Typically, theweight of the tug is about 1,000 tons, so the forces acting upon thecenter of gravity with the joints restrained are about 750 tons or 1.5million pounds. Such forces are encountered when the tug-and-bargecombination is tossed about among waves in heavy seas.

Other forces to be considered, of course, are the thrust from thepropeller, and the steering moment. It can be shown that these arerather small, on the order of the one-tenth that of the forces caused bythe seas, the thrust by the propeller being about 150,000 pounds for a5,000 horsepower tug. The design factors, then, are directed toproviding a linkage which will survive punishment by wave forces, ratherthan factors relating to steering or thrust from the propellers.

The function of the slot 12 and cylindrical member 14 may be appreciatedby roughly approximating the forces in the struts with and without theseelements. Using the assumptions above, and assuming the length from thecenter of gravity of the tug to the stern of the barge to be about 75feet, with the width of the stern of the barge about feet and the angleof the struts with respect to the stem 45 degrees, it can be calculatedthat the forces of tension or compression in the struts l5 and 16 wouldbe about 1.75 million pounds in the embodiment of FIGS. 2 and 3. Incontrast, in a similar structure without the pin and slot, assuming thestruts to be rigid horizontally, forces of almost 50 percent more may beencountered. If the struts are almost parallel to the centerline of thevessels, forces almost double that in the FIG. 2 structure would beencountered. Further, if a recess 18 as in FIG. 4 of 25-foot depth isutilized, the forces under the assumption given could be reduced to thejust slightly greater than 1 million pounds in the struts 15 and 16. Ofcourse, making the recess 18 deeper will bring the center of gravity ofthe tug closer to the center of gravity of the barge, or of the overalltwo vessel combination, and thus reduce the forces encountered evenfurther.

The forces that occur in the struts can be further reduced by changingthe angle of the bars with respect to the stern, a larger angle reducingthe force. Clearly, the pin 14 may be more readily constructed towithstand forces of this nature, than can the struts 15 and 16 alongwith the universal joints 17.

The swivel connections or universal joints 17 may be of the type shownin FIG. 6, although it is noted that there are no specific limitationson the type of joint used, except that the design must be such that theforces encountered may be borne by the unit, and rotation about any axisis permitted. A ball joint may be used in place of the type shown inFIG. 6. For convenience, and also as a safety feature, a quick-releasingmechanism may be included in the joints 17, usually at the tug ends, sothat the tug can be quickly disengaged from the barge. A hydrauliclocking or decoupling mechanism may be provided for this purpose.

As seen in FIGS. 7, 7a and 7b, the pin 14 may be a cylinder attached tothe bow of the tug 10, or the bow itself may be shaped to provide thefunction of the pin. It will be noted that the pin need not be acomplete cylinder, since the tug should not roll more than about 30 ineither direction. Thus, the top and bottom of the pin might be flat, orpreferably a vertical member 19 may extend through the pin 14 as seen inFIG. 7a to limit the rolling movement of the tug with respect to thebarge. This arrangement not only provides a mechanical stop, but alsoincreases the strength of the pin.

Another slight degree of freedom present in the coupling arrangement asdescribed above is that incident to swinging the stern of the tug asoccurs upon dipping of one side of the tug while the other stays at thesame level. Considering FIG. 5a, if the starboard side of the tug sinkswhile the port side remains stationary, the bar 16 remaining of fixedlength, the stern of the tug will swing to the right slightly.Therefore, the pin 14 will turn a small amount within the slot 12. Thismovement is small and will be absorbed by the mechanical clearancebetween the pin and slot, or by the rubber shock absorber as may linethe pin or slot.

Referring to FIG. 7b, it is seen that the bow of the tug itself, ratherthan an attachment or separate member added to the bow, may form theprotrusion 14. In this case the wedgeshaped portions and 21 of the bowextending above and below the member M provide the same function as thekey member 19 in the embodiment of FIG. 7a.

Another embodiment of the invention is shown in FIG. 8; here the bars 15and 16 are connected together at a juncture 22, which in turn isconnected to the bow of the tug It) by a universal or swivel joint 23.The forward ends of the bars 15 and M are connected to the stern of thebarge 11 by hinge joints 24 and 25; these joints permit movement of thebars 15 and 16 only in the vertical direction relative to the barge.Turning, side-to-side, or pivotal movement is unnecessary. The joint 23permits freedom for rolling motion, such movement causing the member 14to turn in the slot 12. To this end, the axis of the fore-and-aft pivotin the joint 23 preferably should be coaxial with the axis of thecylindrical or partially cylindrical member 14, both of these being inthe vertical plane of the centerline of the vessels. In pitching orrolling motions, the member 14 must be permitted to move fore-and-aft inthe slot 12 as before.

Referring to FIGS. 9, 10 and 11, an embodiment of the invention is shownwherein the protruding bow member is formed by a shape portion of thebow of the tug 10. The bow of the tug fits within a recess 18, as in theFIG. 4 embodiment. A wide vertical slot 12' receives the bow member 14',which as seen in FIGS. 10 and II is a large protruding part of the bow.The member 14' has curved sides 28 which are covered by thick bumpers29. The curved shape of the sides 28 and bumpers 29 permits the tug toroll with respect to the barge, but this rolling movement will beimpeded as the more linear shape of the upper portion of the member Mengages the sidewall of the slot 12'. Bumpers 30 are provided on thesides of the recess 18 to absorb impact when pronounced rolling orpitching motion occurs, or when the tug is maneuvering to the make thecoupling. Another bumper 31 on the forward face of the bow member 14cushions contact between the bow member and the forward face of the slot12 as may occur when pitching or upon changes in draft.

Another embodiment of the invention using a rectangularshaped bowmember, instead of a cylindrical or curved shape, is shown in FIG. 12aand FIG. 12b. This embodiment is quite similar to that of FIGS. 9-11,but includes a bow member 32 which is rectangular in shape. The slot 12'is the same as before, as is the recess 18 in the stem of the barge. Theoutside of the bow member 32 is encased in large, thick rubber bumpers33. The thickness of these bumpers 33 may be about 1 foot, and thestructure may be made up of 12 inches X 12 inches rectangular fenders.The vertical height of the bumper 32 may be about 10 feet, and the widthathwart-ships somewhat less. The clearance between the bow member 32 andthe slot 12 permits very slight rolling motion of'the tug relative tothe barge, while the resilient nature of the bumpers accommodatesconsiderable rolling motion. About 5 of relative roll would be possiblewith the coupling described.

The concept of this invention has been thus far described with referenceto embodiments which permit rolling motion of the tug relative to thebarge. However, this feature is not always preferable, and may in somecases be eliminated advantageously. Referring again to FIG. 12a and1212, instead of having resilient bumpers 33 which deform severalinches, the bumpers may be composed of nonyielding material such aswood, so that very little if any rolling motion is possible. In thiscase the bow member 32 and its bumper 33 would fit fairly close in theslot 12', with only enough clearance to allow vertical movement of themember in the slot and pitching movement. In this situation, the bowmember, slots, and struts must be made more sturdy, as more forces willbe applied to them in heavy seas than in the embodiments whereconstraints are not imposed on rolling motion. This embodiment thusconstrains rotary motion about the Y axis as defined above, this beingthe major axis of the bow member itself and also of the tug. However,some freedom of rotation about the X axis is permitted; the X axis isperpendicular to the slot and perpendicular to the axis of the bowmember. Of course, the coupling provides constraint for rotation aboutthe Z axis.

Again referring to FIG. 12b, another feature is shown which has not beenpreviously described. The discussion of FIGS. 12a and 12b given aboveassumes that the feature now to be described was not present. Verticalmovement of the bow member 32 within the slot 12 may be furtherconstrained by a strut 34 which comprises a-hydraulic piston andcylinder arrangement 35 connected by bars 36 and universal or swiveljoints 37 to the tug and barge. The joint 37 at the lower end of thestrut 34 is connected to the bow member 32, and the joint 37 at theupper end is connected to a horizontal beam 38 at the top of the slot12'. The chambers on opposite sides of the piston in the hydrauliccylinder 35 are connected together through a small orifice in thepiston. The orifice permits slow movement of the piston as may occurupon changes in draft of the vessels. However, the piston is notpermitted to move up and down rapidly as would occur during pitchingmovements. The member 32 may still rotate about a horizontal axis topermit relative pitching movements, but this axis will be located at thelower end of the strut 34 rather than at the natural foreand-aft centerof rotation of the tugboat. The constraint of the strut 34 does notprevent slight fore-and-aft movement of the member 32 as may occur inpitching or changes of draft. The strut 34 includes a shock absorbingfunction as provided by the hydraulic cylinder; impact stresses are thusrelieved. An air chamber may also be included to increase theeffectiveness of the shock absorbing function.

The strut 34 of FIG. 12b may be used in anyof the other embodiments ofthe invention, although it is understood that rolling motion would besomewhat impeded by the presence of the strut, and a much moresubstantial strut structure would have to be used to withstand theadditional stress of rolling, compared to that necessary in theembodiment of FIG. 12a and 12b.

In the description of the invention, the struts or bars 15 and 16 areshown or referred to as being of fixed length; by this is meant that thestruts do not contract or expand while in operation aboard vessels atsea. However, it is appropriate that the struts be adjustable so thatthey may be fitted to various tugbarge combinations, or to accommodatewidely varying draft. Once the proper length is set, further changes inlength would be prevented by a locking mechanism. In some cases a shockabsorbing mechanism of very hard characteristics may be approprrate.

The struts may be carried by either the tug or the barge in any of theembodiments described. In one practical embodiment, the struts arecarried by the barge and are spring biased in an upward position whenthe tug is not coupled, so that the struts will not be damaged bycollision with other vessels or wharfs, and will not hang in the water.When the tug approaches from the rear for coupling, the struts may bepulled downward to engage releasable couplings on the sides of the bowsection of the tug. This operation may be performed by persons on thetug, no one need board the barge.

In contrast to tug-and-barge coupling heretofore developed, the presentinvention employs rigid struts which are fixed to the tug and barge byjoining devices which do not allow the ends of the struts to move withrespect to the vessel, except in an angular or pivotal motion as by ahinge or swivel. The ends of the struts do not slide up and down, normove in a fore-andaft direction, nor move athwart-ships.

Although described in the context of embodiments showing the tug pushinga barge, if for some reason it was necessary to have the leading vesselprovide the propulsion thrust, the same principles could apply. Also,even though it is clearly preferable for a tug-barge coupling to havethe slot in the stern of the tug, other vessels may be such that the pinand slot would be reversed.

While the invention has been described with reference to particularembodiments, this description is not meant to be construed in a limitingsense. Various modifications of the disclosed embodiments, as well asfurther embodiments of the invention may be apparent to persons skilledin the art upon reference to this description. It is thereforecontemplated that the appended claims will cover any such modificationsor embodiments as fall within the true scope of the invention.

1 claim:

1. Apparatus for coupling first and second vehicles while permittingcertain freedom of movement of one vehicle relative to the othercomprising:

an elongated slot defined at one end of the first vehicle, the

slot generally facing the second vehicle;

a member protruding from one end of the second vehicle to extend intosaid elongated slot, adapted for freedom of movement along the slot;

elongated means connecting the first and second vehicles to one anotheron both sides of said slot, the elongated means being connected at bothends to the first and second vehicles by swivel or hinge-type joiningmeans; and

said joining means permitting angular pivotal movement of the elongatedmeans with respect to the vehicles, and preventing the ends of theelongated means from moving in a direction parallel to the elongatedslot with respect to the vehicle to which each end is connected.

2. Apparatus according to claim 1 wherein the elongated means aregenerally fixed in length.

3. Apparatus according to claim 1 wherein the elongated means include apair of struts, one on each side of the slot, the struts being connectedto at least one of the vehicles by swiveltype means.

4. Apparatus according to claim 1 wherein the member is shaped to permitrotational motion in the slot.

5. Apparatus according to claim 1 wherein the member is shaped to impederotational motion in the slot.

6. Apparatus according to claim 1 wherein the member has curvedtransverse sides with the major axis of the member being generallyparallel to a path of movement of the first and second vehicles.

7. Apparatus according to claim 1 wherein the elongated slot and themember are of such sizes and lengths to permit a slight movement of thevehicles with respect to one another along an axis generally parallel toa major path of movement of the vehicles, while the coupling apparatuspermits propulsion thrust of one vehicle relative to another.

8. Apparatus according to claim 1 wherein the slot is generally verticaland located along or parallel to a centerline of the first vehicle.

9. Apparatus according to claim 8 wherein the member is at the forwardend of the second vehicle and the slot is at the stem end of the firstvehicle, the vehicles being floating vessels.

10. Apparatus according to claim 9 wherein the elongated means are apair of struts, each extending from a fixed point on the second vesselto a fixed point generally at the stern of the first vessel.

11. Apparatus according to claim 10 wherein the struts are fixed inlength and are connected to the first and second vessels by swivel-typeor universal-type joints.

12. Apparatus according to claim 1 wherein a large recess is provided insaid one end of said first vehicle to receive a major portion of the endof the second vehicle.

13. Apparatus according to claim 12 wherein the first vehicle is a bargeor like floating vessel, and the second vehicle is a tugboat or thelike; the large recess being in the stern of the barge and theprotruding member being at the bow of the tugboat; the elongated means,being a pair of struts of generally fixed length, are on each side ofthe slot, the ends of the struts being connected to the barge andtugboat by swivel-type joinmg means.

14. Apparatus according to claim 13 wherein the member protruding fromthe bow of the tug has substantially straight sides whereby rollingmotion between tugboat and barge is impeded.

15. Apparatus according to claim 13 wherein the member protruding fromthe bow of the tug has curved sides whereby there is substantial freedomfor rolling motion between tug- .boat and barge.

16. Apparatus according to claim 1 wherein the vehicles are floatingvessels, and freedom of movement of the second vehicle relative to thefirst vehicle is provided for movements of pitch, heave, and changes ofdraft, whereas constraint on freedom of movement is provided for yawingand fore-and-aft movements.

17. Apparatus according to claim 16 wherein the constraint uponfore-and-aft movements includes a certain degree of freedom of movementincident to pitching movements.

18. Apparatus according to claim 3 wherein the struts are connectedtogether at one end and are both connected to the second vehicle by asingle swivel-type joint which is located generally along the centerlineof the second vehicle.

19. Apparatus according to claim 18 wherein the other ends of the strutsare connected separately to the first vehicle by hinge-type joints.

20. In apparatus for coupling the bow of a tugboat or the like to thestern of a barge or other vessel, for the purpose of propelling thebarge while permitting certain freedom of movement of the vesselsrelative to one another;

an elongated vertical slot provided at the stern of the barge generallyalong or parallel to the centerline thereof, the slot having opposingvertical walls;

a member protruding from the bow of the tugboat and extending generallyin a forward direction into said vertical slot, the member havinglateral faces for engagement with the walls of the slot, whereby themember in the slot functions to permit freedom of pitching movement ofthe tugboat relative to the barge while impeding athwart-ships movement;and

a pair of elongated generally rigid bars extending from the tug to thestern of the barge, one being located on each side of the slot, the barsbeing laterally spaced from the slot, the bars bearing thrust from thetug to the barge.

21. In a coupling arrangement according to claim 20, the bars beingconnected to the tug and the barge by swivel-type or hinge-type joints.

22. In a coupling arrangement according to claim 21, the slot and themember being of such size and length as to permit slight fore-and-aftmovement incident to pitching and changes of shift.

23. In a coupling arrangement according to claim 20, the sides of themember protruding from the bow being substantially flat and parallel tothe walls of the slot, to impede rolling movement of the tug relative tothe barge.

24. In a coupling arrangement according to claim 20, the sides of themember protruding from the bow being of curved shape to allow somefreedom of rolling movement of the tug relative to the barge.

25. In a coupling arrangement according to claim 20, wherein a largerecess is provided at the stern of the barge to receive a major portionof the bow of the tug, the vertical slot being at the apex of suchrecess.

26. In a coupling arrangement according to claim 20, wherein the memberhas generally curved sides but is shaped near top and bottom to providea mechanical stop to inhibit rolling movement of the tug beyond aselected amount.

27. In a coupling arrangement according to claim 20, the rear ends ofthe bars being connected together and to a universal-type joint which islocated generally along or parallel to the centerline of the tug. I 1

28. In a coupling arrangement according to claim 27, the front ends ofthe bars being connected separately to the stem of the barge 'byhinge-type joints which permit relative movement only in a verticaldirection.

29. In apparatus for-coupling the bow of atugboat or the like to thestern of a barge or other vessel, for the purpose of propelling. thebarge while permitting certain freedom of movement of the vesselsrelative to one another;

an elongated vertical slot provided at the stern of the barge at aboutthe midpoint thereof, the slot having opposing substantially verticalwalls; i

a member protruding from the bow of the tugboat and extending generallyin a forward direction into said vertical slot, the member havinglateral faces engaging the walls of the slot, whereby the member maymove up-and-down in the slot or rotate at least partially about ahorizontal axis, but is prevented from rotating in the slot about avertical axis, the member and slot being of shape and size tosubstantially prevent yawing of the tug relative to the barge but topermit pitching, heaving and changes of draft of the tug relative to thebarge; and

a pair of elongated bars extending from the tug to the stern of thebarge, one being located on each side of the slot.

30. In a coupling arrangement according to claim 29, wherein the slotand the member are of such size and length to permit slight fore-and-aftmovement incident to pitching.

31. In a coupling arrangement according to claim 29,

wherein a large recessis provided at the stern of the barge to receive amajor portion of the bow of the tug, the vertical slot movement.

33. In apparatus according to claim 29, the lateral faces of the memberbeing curved to permit rolling movement.

34. Apparatus for coupling first and secondvehicles while permittingcertain freedom of movement of one vehicle relative to the othercomprising:

an elongated slot defined at one end of the first vehicle, the slotgenerally facing the second vehicle, the slot having opposing walls;

a member protruding from one end of the second vehicle to extend intosaid elongated slot, adapted for freedom of movement along the majoraxis of the slot and adapted for at least partial freedom of rotationalmovement about an axis perpendicular to the major axis of the member andthe slot, the member and slot being of shape and size to substantiallyprevent movement in the direction transverse to the major axes of themember and slot or rotation of the member about an axis parallel to themajor axis of the slot; and

elongated rigid means of fixed length connecting the first and secondvehicles to one another on both sides of said slot, the elongated meansbeing connected at both ends to the first and second vehicles by swivelor hinge-type joints.

35. Apparatus according to claim 34 wherein a large recess is providedin said one end of said first vehicle to receive a major portion of theend of the second vehicle, the recess being at the apex of such recess,the recess being substantially being large enough to permit clearancefor rolling and pitching movements of said end of the second vehiclewith the recess.

36. Apparatus according to claim 34 wherein means are provided forimpeding short-duration vertical movement of the member within the slotas may be caused by pitching or the like while permitting long-durationvertical movement as may be caused by relative changes in draft.

1. Apparatus for coupling first and second vehicles while permittingcertain freedom of movement of one vehicle relative to the othercomprising: an elongated slot defined at one end of the first vehicle,the slot generally facing the second vehicle; a member protruding fromone end of the second vehicle to extend into said elongated slot,adapted for freedom of movement along the slot; elongated meansconnecting the first and second vehicles to one another on both sides ofsaid slot, the elongated means being connected at both ends to the firstand second vehicles by swivel or hinge-type joining means; and saidjoining means permitting angular pivotal movement of the elongated meanswith respect to the vehicles, and preventing the ends of the elongatedmeans from moving in a direction parallel to the elongated slot withrespect to the vehicle to which each end is connected.
 2. Apparatusaccording to claim 1 wherein the elongated means are generally fixed inlength.
 3. Apparatus according to claim 1 wherein the elongated meansinclude a pair of struts, one on each side of the slot, the struts beingconnected to at least one of the vehicles by swivel-type means. 4.Apparatus according to claim 1 wherein the member is shaped to permitrotational motion in the slot.
 5. Apparatus according to claim 1 whereinthe member is shaped to impede rotational motion in the slot. 6.Apparatus according to claim 1 wherein the member has curved transversesides with the major axis of the member being generally parallel to apath of movement of the first and second vehicles.
 7. Apparatusaccording to claim 1 wherein the elongated slot and the member are ofsuch sizes and lengths to permit a slight movement of the vehicles withrespect to one another along an axis generally parallel to a major pathof movement of the vehicles, while the coupling apparatus permitspropulsion thrust of one vehicle relative to another.
 8. Apparatusaccording to claim 1 wherein the slot is generally vertical and locatedalong or parallel to a centerline of the first vehicle.
 9. Apparatusaccording to claim 8 wherein the member is at the forward end of thesecond vehicle and the slot is at the stern end of the first vehicle,the vehicles being floating vessels.
 10. Apparatus according to claim 9wherein the elongated means are a pair of struts, each extending from afixed point on the second vessel to a fixed point generally at the sternof the first vessel.
 11. Apparatus according to claim 10 wherein thestruts are fixed in length and are connected to the first and secondvessels by swivel-type or universal-type joints.
 12. Apparatus accordingto claim 1 wherein a large recess is provided in said one end of saidfirst vehicle to receive a major portion of the end of the secondvehicle.
 13. Apparatus according to claim 12 wherein the first vehicleis a barge or like floating vessel, and the second vehicle is a tugboator the like; the large recess being in the stern of the barge and theprotruding member being at the bow of the tugboat; the elongated means,being a pair of struts of generally fixed length, are on each side ofthe slot, the ends of the struts being connected to the barge andtugboat by swivel-type joining means.
 14. Apparatus according to claim13 wherein the member protruding from the bow of the tug hassubstantially straight sides whereby rolling motion between tugboat andbarge is impeded.
 15. Apparatus according to claim 13 wherein the memberprotruding from the bow of the tug has curved Sides whereby there issubstantial freedom for rolling motion between tugboat and barge. 16.Apparatus according to claim 1 wherein the vehicles are floatingvessels, and freedom of movement of the second vehicle relative to thefirst vehicle is provided for movements of pitch, heave, and changes ofdraft, whereas constraint on freedom of movement is provided for yawingand fore-and-aft movements.
 17. Apparatus according to claim 16 whereinthe constraint upon fore-and-aft movements includes a certain degree offreedom of movement incident to pitching movements.
 18. Apparatusaccording to claim 3 wherein the struts are connected together at oneend and are both connected to the second vehicle by a single swivel-typejoint which is located generally along the centerline of the secondvehicle.
 19. Apparatus according to claim 18 wherein the other ends ofthe struts are connected separately to the first vehicle by hinge-typejoints.
 20. In apparatus for coupling the bow of a tugboat or the liketo the stern of a barge or other vessel, for the purpose of propellingthe barge while permitting certain freedom of movement of the vesselsrelative to one another; an elongated vertical slot provided at thestern of the barge generally along or parallel to the centerlinethereof, the slot having opposing vertical walls; a member protrudingfrom the bow of the tugboat and extending generally in a forwarddirection into said vertical slot, the member having lateral faces forengagement with the walls of the slot, whereby the member in the slotfunctions to permit freedom of pitching movement of the tugboat relativeto the barge while impeding athwart-ships movement; and a pair ofelongated generally rigid bars extending from the tug to the stern ofthe barge, one being located on each side of the slot, the bars beinglaterally spaced from the slot, the bars bearing thrust from the tug tothe barge.
 21. In a coupling arrangement according to claim 20, the barsbeing connected to the tug and the barge by swivel-type or hinge-typejoints.
 22. In a coupling arrangement according to claim 21, the slotand the member being of such size and length as to permit slightfore-and-aft movement incident to pitching and changes of shift.
 23. Ina coupling arrangement according to claim 20, the sides of the memberprotruding from the bow being substantially flat and parallel to thewalls of the slot, to impede rolling movement of the tug relative to thebarge.
 24. In a coupling arrangement according to claim 20, the sides ofthe member protruding from the bow being of curved shape to allow somefreedom of rolling movement of the tug relative to the barge.
 25. In acoupling arrangement according to claim 20, wherein a large recess isprovided at the stern of the barge to receive a major portion of the bowof the tug, the vertical slot being at the apex of such recess.
 26. In acoupling arrangement according to claim 20, wherein the member hasgenerally curved sides but is shaped near top and bottom to provide amechanical stop to inhibit rolling movement of the tug beyond a selectedamount.
 27. In a coupling arrangement according to claim 20, the rearends of the bars being connected together and to a universal-type jointwhich is located generally along or parallel to the centerline of thetug.
 28. In a coupling arrangement according to claim 27, the front endsof the bars being connected separately to the stem of the barge byhinge-type joints which permit relative movement only in a verticaldirection.
 29. In apparatus for coupling the bow of a tugboat or thelike to the stern of a barge or other vessel, for the purpose ofpropelling the barge while permitting certain freedom of movement of thevessels relative to one another; an elongated vertical slot provided atthe stern of the barge at about the midpoint thereof, the slot havingopposing substantially vertical walls; a member protruding from the bowof the tugboat and exteNding generally in a forward direction into saidvertical slot, the member having lateral faces engaging the walls of theslot, whereby the member may move up-and-down in the slot or rotate atleast partially about a horizontal axis, but is prevented from rotatingin the slot about a vertical axis, the member and slot being of shapeand size to substantially prevent yawing of the tug relative to thebarge but to permit pitching, heaving and changes of draft of the tugrelative to the barge; and a pair of elongated bars extending from thetug to the stern of the barge, one being located on each side of theslot.
 30. In a coupling arrangement according to claim 29, wherein theslot and the member are of such size and length to permit slightfore-and-aft movement incident to pitching.
 31. In a couplingarrangement according to claim 29, wherein a large recess is provided atthe stern of the barge to receive a major portion of the bow of the tug,the vertical slot being at the apex of such recess, the recess beingsubstantially larger than the bow of the tug to permit clearance of thebow of the tug within the recess upon pitching movements or the like.32. In apparatus according to claim 29, the lateral faces of the memberbeing substantially vertical to impede rolling movement.
 33. Inapparatus according to claim 29, the lateral faces of the member beingcurved to permit rolling movement.
 34. Apparatus for coupling first andsecond vehicles while permitting certain freedom of movement of onevehicle relative to the other comprising: an elongated slot defined atone end of the first vehicle, the slot generally facing the secondvehicle, the slot having opposing walls; a member protruding from oneend of the second vehicle to extend into said elongated slot, adaptedfor freedom of movement along the major axis of the slot and adapted forat least partial freedom of rotational movement about an axisperpendicular to the major axis of the member and the slot, the memberand slot being of shape and size to substantially prevent movement inthe direction transverse to the major axes of the member and slot orrotation of the member about an axis parallel to the major axis of theslot; and elongated rigid means of fixed length connecting the first andsecond vehicles to one another on both sides of said slot, the elongatedmeans being connected at both ends to the first and second vehicles byswivel or hinge-type joints.
 35. Apparatus according to claim 34 whereina large recess is provided in said one end of said first vehicle toreceive a major portion of the end of the second vehicle, the recessbeing large enough to permit clearance for rolling and pitchingmovements of said end of the second vehicle with the recess. 36.Apparatus according to claim 34 wherein means are provided for impedingshort-duration vertical movement of the member within the slot as may becaused by pitching or the like while permitting long-duration verticalmovement as may be caused by relative changes in draft.